Refrigerating apparatus



June 13, 1933. F. R. BICHOWSKY- 1 6 REFRiEGERATING APPARATUS 2 FiledSept. 7, 1929 2 sheets-sheet 1 f/Lma INVFNTQR ML ATTORNEYS June 13,1933.

. Filed Sept. 7, 1929 F. R. BICHOWSKY REFRIGERATING APPARATUS 2Sheets-Sheet 2 I la CE 2 E a E D. E

PRE55URE,POUWDS-FER S UARE lucH GAUGE.

a m mmWmvrmoR T BY Patented I 13', 193 3 RUSSELL BICHOWSKY, OF WASI HINGTON, DISTRICT OF OOLUHBIA, LSSIGNOB 1'0 FRIGIDAIBE CORPORA-TTON, OFDAYTON,

01110, A conrona'non or nm-awaan mmenna'rme arrana'rus Application filedSeptember 7, 1929. serial 10. 390,009.

This inventionrelates to refrigerating ap-' paratus of theabsorptiontype and particu- .larly to absorbents' and refrigerants for suchapparatus. e of the objects of the invention is to rovide an improvedabsorption refrigeratmg apparatus which may be effectively operated withair cooling.

More specifically it is an object to provide a solid absorbentorreactant material in combination with a suitable refrigerant which maybe operated at temperatures attainable with ordinary atmosphericconditions to prourposes.

Further objects present invention will be apparent from the followingdescription, reference being bad to'the accompanying drawings, wherein apreferred form of the invention is clearly shown.

In the drawings:

Fi 1 isa diagrammatic representation of a re rigerating apparatus inwhich the inp vention may be empluyed -Fig. 2 is a constant pressurecooling and heating curve, showing the temperatures of a representativereactant material in absorbing and liberating a representativerefrigerant; and

Fig. 3is a graph showing the vapor pressure characteristics of arepresentative refrigerant and of. a representative absorbent.

In refrigerating apparatus of the absorption type use is made .of areactant material, which 'upon being cooled absorbs or takes up -a'refrigerant vapor at a low pressure to permit evaporation of refrigerantat a low temrature and thus produce refrigeration.

hereafter the reactant material is heated to drive of! or emit itsabsorbed refrigerant at a high pressure which permits the condensationof the refrigerant. It is desirable to use a solid reactant materialbecause thistype of material permits the formation of a permanent, stabe,'porous structure through which the refrigerant readily permeates, andbecausethe use of a solid reactant eliminatesthe objectionable featureof liquid reactants,

15 duce temperatures suitable for refrigeration and advantages of theducing a low pressure namely distilling from the solution with therefrigerant.

While absorption refrigerating machines using solid reactantshaveheretofore been known, it is necessary to cool these machines withwater because the temperature to which the reactant must be cooled inorder to take up refrigerant at a sufiiciently low pressure is v too lowto be accomplished by air cooling. In consequence these machines are ofthe nature of more or less permanent installations which require water.supply and waste connections. These objections seriouslyv limit theportability of refrigerating machines and curtail their utility, as wellas increase their operating cost.

My invention is'concerned with providing small refrigerating plants ofthe solid reactant type which can be readily cooled by air and which arereadily portable, have large refrigerating capacity for a unit of givensize, and are economical to operate. Referring to Fig. 1, thegenerator-absorber roper is a container 10 which is filled with thesolid reactant material and which may be provided with any suitableinternal arrangement of plates or fins for conducting the heatthroughout the reactant material. The generator-absorber may beconnected through a condenser 12 to a, refrigerating element in whichthe phase state of the refrigerant is changed to causethe refrigerant toabsorb heat. This refrigerating element may be, but is not necessarilyan evaporator 14. The evaporator 14 may consist pf .an insulatedreceiver 16 and refrigerant circulating tubes 18 which are exposed tothe space to-be refrigerated. When 1 the generator-absorber 1sheatedgaseous refrigerant is evolved which is condensed in the condenser12 and flows in liquid form to the receiver 16. The tubes 18 are keptfilled with liquid refrigerant at all times so that the gaseousrefrigerant flowing to the condenser during the initial stage of theevolution period will not transmit heat' to the space to berefrigerated, and will thus enforce condensation in the condenser. Whenthe generator-absorber is cooled, the reactant material absorbs therefrigerant vapor, ro-

throughout the re rigerant circuit whichllpermits the evaporation 7generator absorber is enclosed in a vapor shell 20 which may be filledto the level 22 with.

an suitable volatile liquid, for exam le alcoho An electric heatingelement iagrammatically indicated at 24: is placed in the lower part ofthe vapor shell. The top of g the vapor shell is connected by theconduit 7 quantity 0 32 is closed the vapor pressure forces the 26 withone end of the vapor condenser 28, the other end of which is connectedby conduit 30 with the bottom of the vapor shell. "A valve 32 is placedin the conduit 26 for opening and closing the latter as willbeexplained. ,A feature of the invention is the cooling of the refrigerantcondenser and the generatoralosorber by air. For this purpose I placethe refrigerant condenser 12 and the vapor condenser 28 in a flue 34through which a current of air is constantly circulated by fan 36. Whenthe generator-absorber is to be heated electric current is supplied tothe heating element 34 and the valve 32 is closed. The heatin of thealcohol vaporizes a small 6 the liquid and because the valve liquidalcohol through the conduit 30 up into the condenser 28. The capacitiesof the vapor shell and the condenser 28 are so related to each otherthat the condenser 28 is filled when the level of the alcohol is loweredto the line 38. Liquid alcohol is held inert in the condenser, and the.liquid remaining in the shell 20 vaporizes and condenses on the surfaceof the generator-absorber, supplying heat to the latter. The refrigerantevo ved is condensed in the condenser 12 by'the current of air and flowsto the evaporator.

When the generator absorber is to be cooled the heating element 24=isturned 06? and the valve 32 in the conduit 26 is opened. The a1- coholvapor then hows a into the vapor condenser 28, and the liquid flows backto the vapor shell 20 immersing the generator-absorber to the level 22.The cold liquid alcohol is vaporized by the hot generator-absorber andthe vapor flows up through conduit 26 into the condenser 28 where it isliquefied by the current at air, liquid flowing back through the shellto the pipe 30. This evaporation and condensation of the alcohol coolsthe generator-absorber to withdraw refrigerant from the evaporator.

Any suitable arran ment me he used for automatically controlling theheating and cooling of the generator-absorber in respo to refrigerarequirements. For exam Fe aeiaeee 56 with the other side of the sourceof power 44. When this connection is established current energizes thesolenoidto attract the core 58 which moves the switch 54 to the leftinto the position shown in the drawings. This breaks the circuit betweenwires 52 and 56, deenergizing the solenoid 50. The switch remains inthis position and establishes a circuit to the heating element throughwire 56, switch 54, wires 60, 62 and 64 to one side of the heatingelement 24, thencethrough wires 66 and 68 which are permanentlyconnected to the source of power M. Simultaneously the circuit iscompleted through the valve operating solenoid 70 as follows: wire 56,switch 54, wires 60, 62 and72 to the solenoid thence from the solenoidby wires 74 and 68 back to the source'of power. Energizing the solenoid70 draws aplunger 7 6 tothe left against a force of a spring 78 andcloses the valve-32. Thus movement of the switch 54 to the left wheneverthe float 40 reaches its lower position as indicated in the figurestarts a heating period and distills refrigerant into the receiver 16.When the refrigerant in the receiver reaches a predetermined'high levelthe float switch makes cbntact with the high level contact 80. Thisestablishes a circuit through another switch operatin solenoid 82 asfollows: from the source 0 power it through wire 42, switch 40, contact80, wire 84 to the solenoid 82, thence from the solenoid 82 through.wire 86, wire 60, switch .54, and wire 56 back to the source of power.Energizing the solenoid 82 moves the switch contact 54 to the right inthe position connecting wires 56 and 52 (so that solenoid 56 may beenergized when lower level is reached) and deenergizes the solenoid 82,heater 2t and valve solenoid 70, permitting the s ring 78 to open thevalve and permit circu ation of the alcohol for cooling thegeneratorabsorber.

Since air temperatures of 100 to F.

will be encountered, apparatus must be rovided which will dissipate tothe atmosphere at this temperature the heat absorbed from the space tobe refrigerated. Since solid toactants are poor conductors of heat, inan apparatus of thistype a tem erature diilerential of 30 to 40 18require to produce satisfact/(wily rapid heat flow from the reactantmaterial to the outside air. This means that the reactant material, whencooled to or F. must absorb the refrigerant at a 'suficiently lowrefrigerant pressure to perunit the change of phase state of therefriger= apt in the refrigerating element at temperameans that thereactant must give off 'refrigerant vapor which can change its phasestate (liquefy) in an air cooled condenser. The temperature differentialwhich is required to remove heat from metal conduit in which gaseousrefrigerant is flowing is less than that required to remove heatfromsolid reactant material. The temperature differential required forcondensation may be for example This requires the reactant to emitrefrigerant at a refrigerant pressure which will ,permitcondensation atapproximately 120 F. Obviously the temperature at which such emissiontakes place must be within reasonable limits which can readily beobtained in household appliances, for example 500 F.

In addition to the temperature conditions which the reactant materialmust meet the material must be stable throughout the range of operationof the refrigerating apparatus; That is, at the temperaturesencountered, while the substances may changetheir'chemical and physicalform during different periods of operation, they must be capable ofreturning to their original physical and chemical condition in orderthat the refrigerating cycle may be repeated, and must notv react witheach other or with the materials of which the apparatus is constructedto form chemical compounds other than the refrigerant and reactant.-

' As refrigerant, I prefer to use, ammonia. In order to provide suitablematerials which can be used as reactants in air-cooled refrigeratingmachines, I have investigated the properties of a large number ofchemical compounds and I find that there are a. number of compounds,namely, M1101 .MnBr FeCl FeBr and 00012, which have a chemical aflinit-yfor ammonia and possess the property of uniting with the ammonia to formother chemical compounds known as addition compounds, ammines orammoniates, in which each molecule of the substance holds in chemicalcombination one or a number of molecules of the refrigerant. Usuallyeach substance mentioned is capable of combining with different numbersof molecules of the refrigerant so as to form several different additioncompounds, which latter are described as of low order or high orderaccording to whether there is a small or large number of molecules ofrefrigerant held in combination with each molecule of the sub-. stance.The lower order addition compounds will, under suitable conditions, ab-

sorb or combine with refrigerant to form higher order additioncompounds, and thus produce refrigeration. The process is com pletelyreversible, so that the higher order addition compounds can bedissociated into lower order addition compounds and free refrigerantwhich latter can be liquefied to be used again.

These substances as well as their various addition products are suitablefor use as reactants in combination with ammonia.

As an example of the substance listed consider manganese chloride. Thishas the roperty of combining with ammonia, to orm a variety of additioncompounds. Fig. 2 shows the behaviorof manganese chloride and itsaddition products with ammonia at various temperatures and at a pressureofone atmosphere. At a temperature of approximately 675 F. gaseousammonia are in each other. I move the latent heat evolved by chemicalcombination the two substances will combine at a constant temperature toform an addition compound of the first order, namely manganesechloride-1 ammine, of the formula MnCl .NH The temperature will remainconstant as shown by the portion AB of the curve as long as the heat isremoved and there are MnCl and NH, to combine. After the chemicalcombination is complete further cooling will reduce the temperature asindicated by the portion BC of the curve until at a temperature ofapproximately 485 F. the MnCl .NH again combines with ammonia, formingmanganese chloride-2 ammine, Mn'Cl .2NH which is an addition product ofthe second order. As long as the manganese chloride-1 ammine is beingconequilibrium with manganese chloride and If the MnCl is cooled toreverted into manganese chloride-2 ammine the temperature will remainconstant at 485 as shown by the portion CD of the curve. After thiscombination is complete, further cooling will reduce the temperatures ofthe mass of material as'shown by the portion DE until at the temperatureof approximately 185 F. the manganese chloride-2 ammine will again takeup ammonia forming manganese chloride-6 ammine Mncl fiNH an additionproduct of the sixthorder. This occurs at a-constant temperature asindicated by EF of the curve. Any of the addition products mentioned maybe dissociated into gaseous ammonia and the addition products of thenext lower order by supplying the heat of dissociation at thetemperature of equilibrium. Suppose the direction of heat flow isreversed at the point F, and thereafter heat is supplied to thematerial. Then a molecule of manganese chloride-6 ammine at atemperature of approximately 185 F.

dissociates into a molecule of manganese breaks down into a molecule ofmanganese,

chloride-1 ammlne and one molecule of ammonia. While this dissociationis taking place the temperature will remain constant and afterdissociation is complete further heating will elevate the temperature asshown in the portion TK of the curve until at the temperature of 675 F.the last remainin molecule of ammonia will be evolve the manganesechloride-l ammine bein converted into pure manganese chloride nCl Eachof the addition products is a suitable reactant to be used with therefrigerant ammonia. The temperatures at which the described reactionsoccur are dependent upon the pressure. Fig. 3 shows the pressures andtemperatures for equilibrium conditions between ammonia, and the higheraddition products of manganese chloride as well as the vapor pressurecharacteristics of ammonia.

From this figure it will be .seen that at a pressure of approximately 40pounds per square inch gauge, ammonia boils at a temperature ofapproximately 25 F. Likewise at the pressure of 40 lbs. manganesechloride- 6 ammine is in equilibrium with ammonia at a temperature ofapproximately 240. Consequently if manganese chloride, or any of itslower-order addition products is cooled at this temperature, ammoniawill be absorbed to form MnCl fiNH This will permit evaporation of theammonia at a temperature of 25, thus producing useful refrigeration. Thetemperature of 240 is easily obtained in the absorber by means of theair cooling arrangement shown in Fig. 1.

Likewise from Fig. 3 it will be seen that at a pressure of 260 lbs.ammonia will condense at a temperature of approximately 120 F. At thepressure of 260 lbs. manganese chloride-6 is in equilibrium with ammoniaat temperature of 320 F. Consequently if the reactant is heated to thistemperature gaseous ammonia will be evolved at a sufliciently highpressure to be condensed in a condenser cooled at 120.

It will be observed that for each molecule of the reactant fourmolecules of ammonia are cyclically emitted and absorbed. The

molecular volume of MnCl is approximately twice that of ammonia, so thatthe product lllnCl fiNll-lmay be said to have a unit refrigerant. Thisprovides an absorbent of relatively large refrigerating capacity perunit volume.

Manganese chloride and ammonia are explained merely for illustration ofthe reactions which occur, but it will be understood that the inventionmay be practiced with other reactant and/or refrigerants.

The salts listed all behave in the same general way with the ammonia asdoes manganese chloride, the reactions taking place at differingtemperatures and pressures and involving differing amounts of reactantand refrigerant.

However, all of the substances listed and/ or some of their additionproducts when cooled to temperatures not less than 140 F. absorbsatisfactory quantities of ammonia at pressures of 40 pounds gauge orless (and thus provide refrigerating temperatures of 25 F, or less), andthe addition products so formed, when heated to temperatures below 500F., evolve the absorbed ammonia at a pressure of 260 pounds gauge ormore, which permits the ammonia to be condensed at a temperature notless than 120 F. Consequently any of these substances areadapted to beused as absorbents or reactants in aircooled refrigerating apparatuswherein ammonia is used as the refrigerant.

The invention has been illustrated as applied to a refrigerating systemin which refrigeration is produced by the evaporation of a liquidrefrigerant. However, the invention is not limited to such systems, butis applicable to any system in which the phase state of the refrigerantis changed to absorb heat. For example, the invention may be applied tosystems in which the refrigerant changes from a solid phase to a vaporphase in the refrigerating element.

Furthermore, the invention is not limited to any particular form ofapparatus, nor to any specific materials, but embraces such apparatusand materials as fall within the scope of the following claims.

ll claim: I

1. Refrigerating apparatus of the intermittent absorption type includinga generator-absorber and an evaporator, means for heating and coolinsaid generator-absorber including a closed circuit containing thevolatile fluid, said circuit having a porton in heat exchange relationwith the generator-absorber and a portion remote from thegenerator-absorber and constituting a condenser, means for heating saidcircuit and means for air cooling said condenser portion.

' 2. Refrigerating apparatus of the intermittent absorption typeincluding a generator-absorber and an evaporator, means for heating andcooling said generator-absorber including a closed circuit containing avolatile fluid, said circuit having a portion in heat exchange relationwith the generator ml absorber and a portion remote {pom theenerator-absorber and constituting a con enser, means for heating saidcircuit and means for air cooling said condenser portion, said circuithaving a valve therein and means automaticall operated in response tothe level of liqui in said evaporator for closing said valve during theheating period.

3. Refrigerating apparatus of the intermittent absorption type includinga generator-absorber, a condenser and an evaporator, means for heatingand cooling said generator-absorber includin a closed circuit containinga volatile flui said circuit having a portioninheatexchangerelationwiththegenerator-absorber'an'd a portion remote from thegenerator-absorber and constituting a secondary condenser, a flueenclosing said primary and secondary condensers and means forcirculating air through said flue for cool- 7 ing said condensers.

4. Refrigerating apparatus of the intermittent absorption type includinga generator-absorber, a condenser and an evaporator,- means for heatingand cooling said generator-absorber includin a closed circuit containinga volatile fiui said circuit having a portion in heat exchan e relationwith the generator-absorber an a portion "remote from thegenerator-absorber and constituting asecondar condenser, means forheating said circuit an means for air cooling said condenser,saidsecondary condenser, and means responsive to the level of liquid in saidevaporator for automaticall starting and stopping said second nameheating means.

5. Refrigerating apparatus of the inter mittent absorption typeincluding a generator-absorber, a condenser, and an evaporator, meansfor heatin and cooling said generator-absorber inclu ing-a closedcircuit con taining a volatile fluid, said circuit having a portion inheat exchan e relation with the enerator-absorber an a portion remoteromthe generator constituting a secondary condenser, means for heatingsaidcircult and means for air coolin said condensers. In testimonywhereo I hereto afiix my vs1 ature. RANCIS RUSSELL BICHOWSKY.

